diff --git a/src/table/unmovable_land.h b/src/table/unmovable_land.h
index 780b96ec22..5acc8ca113 100644
--- a/src/table/unmovable_land.h
+++ b/src/table/unmovable_land.h
@@ -125,9 +125,9 @@ static const DrawTileSprites _unmovable_hq[] = {
 
 /** Specification of the original unmovable structures. */
 static const UnmovableSpec _original_unmovable[] = {
-	{ STR_LAI_UNMOVABLE_DESCRIPTION_TRANSMITTER,          0x11,   1,   1 },
-	{ STR_LAI_UNMOVABLE_DESCRIPTION_LIGHTHOUSE,           0x11,   1,   1 },
-	{ STR_TOWN_BUILDING_NAME_STATUE_1,                    0x11,   1,   1 },
-	{ STR_LAI_UNMOVABLE_DESCRIPTION_COMPANY_OWNED_LAND,   0x11,  10,   2 },
-	{ STR_LAI_UNMOVABLE_DESCRIPTION_COMPANY_HEADQUARTERS, 0x22,   1,   1 },
+	{ STR_LAI_UNMOVABLE_DESCRIPTION_TRANSMITTER,          0x11,   1,   1, OBJECT_FLAG_CANNOT_REMOVE | OBJECT_FLAG_REQUIRE_FLAT },
+	{ STR_LAI_UNMOVABLE_DESCRIPTION_LIGHTHOUSE,           0x11,   1,   1, OBJECT_FLAG_CANNOT_REMOVE | OBJECT_FLAG_REQUIRE_FLAT },
+	{ STR_TOWN_BUILDING_NAME_STATUE_1,                    0x11,   1,   1, OBJECT_FLAG_CANNOT_REMOVE },
+	{ STR_LAI_UNMOVABLE_DESCRIPTION_COMPANY_OWNED_LAND,   0x11,  10,   2, OBJECT_FLAG_AUTOREMOVE | OBJECT_FLAG_CLEAR_INCOME | OBJECT_FLAG_HAS_NO_FOUNDATION | OBJECT_FLAG_ALLOW_UNDER_BRIDGE },
+	{ STR_LAI_UNMOVABLE_DESCRIPTION_COMPANY_HEADQUARTERS, 0x22,   1,   1, OBJECT_FLAG_CANNOT_REMOVE },
 };
diff --git a/src/tunnelbridge_cmd.cpp b/src/tunnelbridge_cmd.cpp
index 29e178bc99..0437e9ea54 100644
--- a/src/tunnelbridge_cmd.cpp
+++ b/src/tunnelbridge_cmd.cpp
@@ -16,7 +16,7 @@
 #include "stdafx.h"
 #include "rail_map.h"
 #include "landscape.h"
-#include "unmovable_map.h"
+#include "unmovable.h"
 #include "viewport_func.h"
 #include "cmd_helper.h"
 #include "command_func.h"
@@ -395,9 +395,11 @@ CommandCost CmdBuildBridge(TileIndex end_tile, DoCommandFlag flags, uint32 p1, u
 					if (z_start < GetBridgeHeight(tile)) goto not_valid_below;
 					break;
 
-				case MP_UNMOVABLE:
-					if (!IsOwnedLand(tile)) goto not_valid_below;
+				case MP_UNMOVABLE: {
+					const UnmovableSpec *spec = UnmovableSpec::GetByTile(tile);
+					if ((spec->flags & OBJECT_FLAG_ALLOW_UNDER_BRIDGE) == 0) goto not_valid_below;
 					break;
+				}
 
 				case MP_CLEAR:
 					break;
diff --git a/src/unmovable.h b/src/unmovable.h
index 8f3431e660..366889a7db 100644
--- a/src/unmovable.h
+++ b/src/unmovable.h
@@ -36,12 +36,33 @@ void UpdateCompanyHQ(Company *c, uint score);
 void BuildUnmovable(UnmovableType type, TileIndex tile, CompanyID owner = OWNER_NONE, uint index = 0);
 
 
+/** Various object behaviours. */
+enum ObjectFlags {
+	OBJECT_FLAG_NONE               =       0, ///< Just nothing.
+	OBJECT_FLAG_ONLY_IN_SCENEDIT   = 1 <<  0, ///< Object can only be constructed in the scenario editor.
+	OBJECT_FLAG_CANNOT_REMOVE      = 1 <<  1, ///< Object can not be removed.
+	OBJECT_FLAG_AUTOREMOVE         = 1 <<  2, ///< Object get automatically removed (like "owned land").
+	OBJECT_FLAG_BUILT_ON_WATER     = 1 <<  3, ///< Object can be built on water (not required).
+	OBJECT_FLAG_CLEAR_INCOME       = 1 <<  4, ///< When object is cleared a positive income is generated instead of a cost.
+	OBJECT_FLAG_HAS_NO_FOUNDATION  = 1 <<  5, ///< Do not display foundations when on a slope.
+	OBJECT_FLAG_ANIMATION          = 1 <<  6, ///< Object has animated tiles.
+	OBJECT_FLAG_ONLY_IN_GAME       = 1 <<  7, ///< Object can only be built in game.
+	OBJECT_FLAG_2CC_COLOUR         = 1 <<  8, ///< Object wants 2CC colour mapping.
+	OBJECT_FLAG_NOT_ON_LAND        = 1 <<  9, ///< Object can not be on land, implicitly sets #OBJECT_FLAG_BUILT_ON_WATER.
+	OBJECT_FLAG_DRAW_WATER         = 1 << 10, ///< Object wants to be drawn on water.
+	OBJECT_FLAG_ALLOW_UNDER_BRIDGE = 1 << 11, ///< Object can built under a bridge.
+	OBJECT_FLAG_REQUIRE_FLAT       = 1 << 12, ///< Object can only be build of flat land, i.e. not on foundations!
+};
+DECLARE_ENUM_AS_BIT_SET(ObjectFlags)
+
+
 /** An (unmovable) object that isn't use for transport, industries or houses. */
 struct UnmovableSpec {
 	StringID name;               ///< The name for this object.
 	uint8 size;                  ///< The size of this objects; low nibble for X, high nibble for Y.
 	uint8 build_cost_multiplier; ///< Build cost multiplier per tile.
 	uint8 clear_cost_multiplier; ///< Clear cost multiplier per tile.
+	ObjectFlags flags;           ///< Flags/settings related to the object.
 
 	/**
 	 * Get the cost for building a structure of this type.
diff --git a/src/unmovable_cmd.cpp b/src/unmovable_cmd.cpp
index b2868fe0be..652b31422c 100644
--- a/src/unmovable_cmd.cpp
+++ b/src/unmovable_cmd.cpp
@@ -245,7 +245,8 @@ static Foundation GetFoundation_Unmovable(TileIndex tile, Slope tileh);
 static void DrawTile_Unmovable(TileInfo *ti)
 {
 	UnmovableType type = GetUnmovableType(ti->tile);
-	if (type != UNMOVABLE_OWNED_LAND) DrawFoundation(ti, GetFoundation_Unmovable(ti->tile, ti->tileh));
+	const UnmovableSpec *spec = UnmovableSpec::Get(type);
+	if ((spec->flags & OBJECT_FLAG_HAS_NO_FOUNDATION) == 0) DrawFoundation(ti, GetFoundation_Unmovable(ti->tile, ti->tileh));
 
 	const DrawTileSprites *dts = NULL;
 	Owner to = GetTileOwner(ti->tile);
@@ -258,7 +259,19 @@ static void DrawTile_Unmovable(TileInfo *ti)
 		dts = &_unmovables[type];
 	}
 
-	DrawGroundSprite(dts->ground.sprite, palette);
+	if (spec->flags & OBJECT_FLAG_HAS_NO_FOUNDATION) {
+		/* If an object has no foundation, but tries to draw a (flat) ground
+		 * type... we have to be nice and convert that for them. */
+		switch (dts->ground.sprite) {
+			case SPR_FLAT_BARE_LAND:          DrawClearLandTile(ti, 0); break;
+			case SPR_FLAT_1_THIRD_GRASS_TILE: DrawClearLandTile(ti, 1); break;
+			case SPR_FLAT_2_THIRD_GRASS_TILE: DrawClearLandTile(ti, 2); break;
+			case SPR_FLAT_GRASS_TILE:         DrawClearLandTile(ti, 3); break;
+			default: DrawGroundSprite(dts->ground.sprite, palette);     break;
+		}
+	} else {
+		DrawGroundSprite(dts->ground.sprite, palette);
+	}
 
 	if (!IsInvisibilitySet(TO_STRUCTURES)) {
 		const DrawTileSeqStruct *dtss;
@@ -273,7 +286,7 @@ static void DrawTile_Unmovable(TileInfo *ti)
 		}
 	}
 
-	if (type == UNMOVABLE_OWNED_LAND) DrawBridgeMiddle(ti);
+	if (spec->flags & OBJECT_FLAG_ALLOW_UNDER_BRIDGE) DrawBridgeMiddle(ti);
 }
 
 static uint GetSlopeZ_Unmovable(TileIndex tile, uint x, uint y)
@@ -537,13 +550,19 @@ static void ChangeTileOwner_Unmovable(TileIndex tile, Owner old_owner, Owner new
 
 static CommandCost TerraformTile_Unmovable(TileIndex tile, DoCommandFlag flags, uint z_new, Slope tileh_new)
 {
-	/* Owned land remains unsold */
-	if (IsOwnedLand(tile)) {
-		CommandCost ret = CheckTileOwnership(tile);
-		if (ret.Succeeded()) return CommandCost();
+	UnmovableType type = GetUnmovableType(tile);
+	const UnmovableSpec *spec = UnmovableSpec::Get(type);
+
+	if (spec->flags & OBJECT_FLAG_REQUIRE_FLAT) {
+		/* If a flat tile is required by the object, then terraforming is never good. */
+		return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
 	}
 
-	if (AutoslopeEnabled() && (IsStatue(tile) || IsCompanyHQ(tile))) {
+	if (IsOwnedLand(tile)) {
+		/* Owned land remains unsold */
+		CommandCost ret = CheckTileOwnership(tile);
+		if (ret.Succeeded()) return CommandCost();
+	} else if (AutoslopeEnabled()) {
 		if (!IsSteepSlope(tileh_new) && (z_new + GetSlopeMaxZ(tileh_new) == GetTileMaxZ(tile))) return CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_FOUNDATION]);
 	}